1. Field of the Invention
The present invention relates to a data communication system and a data receiving apparatus to be used for such data communication system. More particularly, the present invention relates to such a data communication system capable of selectively receiving data solely required for user by way of utilizing existing broadcasting facilities without requiring specific broadcast facilities even when volume of broadcast data becomes excessively large, and yet, the present invention also relates to a data receiving apparatus to be used for this data communication system.
2. Description of the Related Art
In consideration of existing problems such as difficulty to obtain unpredictable data like news reports at an appropriate timing during communication via personal computers and also due to such a difficulty to precisely set up required data in the character multiplex broadcast system, the Japanese Laid-Open Patent Publication No. HEISEI-8-8859/1996 has proposed such a data communication system which is constructed to add classification codes to character data or the like in accordance with the data contents for broadcasting and enables a portable terminal apparatus to select character data or the like in accordance with classification codes received from another communication system before receiving the character data.
According to the Japanese Laid-Open Patent Publication No. HEISEI-8-8859/1996, in the above-referred data communication system, it is possible for such a portable terminal apparatus capable of receiving data broadcast via addition of individual classification codes per news report to automatically receive the latest news as much desired as possible any time and anywhere by selecting news reports via classification codes received from another communication system.
Nevertheless, the data communication system disclosed in the above-cited Japanese Laid-Open Patent Publication No. HEISEI-8-8859/1996 still had such a problem to solve in that the system was invented to quickly and selectively receive character data such as news reports requiring the prompt delivery of news contents, and thus, when excessive data has been broadcast, it is impracticable for user to solely receive such a data actually being required.
More particularly, it is expected that the number of channels in the digital broadcast system will greatly be increased in the near future to cause an enormous amount of data to be broadcast, and yet, individuals, shops, restaurants, and others, will also transmit data messages via receivable short-distance broadcast systems within specific local areas to cause the data amount to be increased furthermore. However, in the above-cited data communication system, the above-referred classification codes added to character data or the like are solely related to the contents of the data such as character data to be broadcast, and yet, only a single classification code is added to character data or the like. As a result, in the event that the amount of data for broadcasting has ever been increased excessively, it is quite difficult for any user to selectively receive such a data actually being required.